Impact of Covid-19 lockdowns on the anthropometric development in primary school children in the Rhein-Neckar Region, Germany

Published data suggests that lockdowns during the COVID-19 pandemic may have negatively affected children’s weight development. This study aims to assess the prevalence of overweight and obesity after the COVID-19 lockdowns as well as anthropometric development among primary school children in the Rhein-Neckar Region, Germany. In this cross-sectional study, schools were selected in cooperation with the local health authority to include different socioeconomic backgrounds. Participation was voluntary at school and individual level, requiring written informed consent from legal guardians. Study visits in schools were conducted between October 2021 and July 2022. Anthropometric data from nationally recommended medical examinations at 4 years (U8) and 5 years (U9), data on nutrition, physical activity, and socioeconomic data was collected using questionnaires. zBMI and weight category were calculated based on German reference data. 256 children with a mean age of 8.0 years (7.1–9.3 years) were included in the study. Most participants were from households with an above average income. 5.1% of the children were overweight, 4.7% were obese, 15.6% were underweight, and 74.6% were normal weight with a mean zBMI of -0.25 (SD 1.10), which is significantly lower than the mean zBMI of the German reference population (p < 0.001). No significant changes in zBMI were observed between U8 and U9 (p = 0.16). The mean zBMI decreased by 0.17 (SD 0.72) between U9 and the study visit (p = 0.02). A zBMI decrease of 0.5 was documented for the subgroup of overweight and obese children (p = 0.028) as well as a decrease of 0.23 (SD 0.63) for the normal-weight children subgroup (p < 0.001). Contrary to previous reports mean zBMI decreased significantly in the children studied. No significant changes in zBMI were observed between U8 and U9 examinations, which supports the hypothesis that the decrease in zBMI could be attributed to lockdown measures. The study was registered at clinicaltrials.gov on September 21st 2021 under the registration number NCT05077059.